In the U.S. you can definitely use school facilities after hours (such as the fields, and even some buildings, etc).

The primary concern with not allowing access at any time of day to the general public is of course, the children.

> you can definitely use school facilities after hours

Aside from a few things like some playgrounds shared with public parks next door this has often been pretty untrue. I've definitely had police escort me off school basketball courts when school isn't in session, the natatoriums haven't had much public access, it's not like the school libraries are open after hours, etc.

I'm sure some places are more open and some are less open, I wouldn't say you can "definitely" use them.

I'm not aware of any public schools in my area that would allow me to, e.g., use the basketball court or soccer field after school hours or on the weekends.

Have you tried? I've certainly been able to. And I'm definitely not alone in having used those facilities. I've used them personally and for ad-hoc sport events (lacrosse isn't exactly popular in the area I'm in right now).

Not recently, though I have observed locked doors and gates that make it pretty difficult to use. If your caveat is you need to call ahead to organize an event that's a pretty different use-case from what I'd like to do, which is to use them very casually and occasionally.

That probably says more about the area you live in than the public schools.

Around here the grounds are not only open outside of school hours, but explicitly so (they have closing hours posted: 9PM).

I'd argue there should be some access to school facilities by the public if you want to call them "public". Otherwise it's about as public as the police department.